the problem was solved by replacing the non-Xerox cartridge with a real Xerox cartridge. (They look the same but I guess there's some minor difference that the copier looks for and rejects when it's not genuine)
Simple answer but effective.
I replaced a spent black cart and the LD cart I used in its place threw this error.
I had no genuine Xerox cart, but an extra E-Mall cart I had worked.
Minutes later the LD Cyan wasn't recognized at all! (LD had done just fine for me previously. Now I get TWO duds? Hmmmmm.)
Anyway, replacing the cart was an effective answer for me too.
Turning off the maching and waiting 10 seconds didn't make a difference.
Changing cartridges was the key. I changed all cartridges and the problem was solved. I know it's not the most economical fix, but here's why I did it:
Note: I did not replace with Xerox cartridges but with LD brand.